This application is submitted in response to Request for Applications RFA-HD-08-013, Gender, Youth and HIV Risk (R01). The broad, long-term objective of the proposed research is to develop and test the efficacy of a theory-based, culturally and contextually competent, and gender-specific behavioral intervention to reduce the risk of sexually transmitted diseases (STDs), including HIV, among African American young men 18 to 24 years of age. The Specific Aims are focused on testing the intervention's effects on sexual behavior and STD incidence and testing the mediation of effects of the intervention. African American young men have some of the highest rates of STDs among men in the United States. Efforts to reduce their risk of STD have been hampered by the lack of sexual risk-reduction interventions with solid evidence of efficacy and the inability to identify how to reach this population. We propose to test an intervention for this population in barbershops, which may be an excellent setting in which to engage African American young men in risk-reduction education. The design of the study is a cluster randomized controlled trial. We will stratify on key characteristics, barbershops in zip codes of Philadelphia, PA with the highest rates of AIDS and match them in pairs. We will randomly select 24 matched-pairs and within each pair, randomly assign the barbershops to one of two brief structurally similar small-group interventions led by a male barber facilitator: a 3-hour HIV/STD Risk-Reduction Intervention or a 3-hour violence prevention intervention that will serve as the control. We will enroll in the trial 24 men from each barbershop, for a total of 1,152 participants. Social cognitive theory, the theory of reasoned action/planned behavior, and the applicant's preliminary studies with the population will guide the development of the intervention. The primary outcomes are self-reported condom use, multiple sexual partners, unprotected sexual intercourse, and sexual intercourse assessed at baseline and 6- and 12-month follow-up via audio computer-assisted self-interviewing (ACASI). Secondary outcomes include STDs based on DNA amplification tests on urine specimens and theoretically relevant variables hypothesized to mediate intervention effects, including intentions, beliefs, and self-efficacy. The proposed research has great public health significance: about one-half the cases of HIV/AIDS worldwide are linked to sexual relations between men and women, but few randomized controlled trials have tested HIV/STD risk-reduction interventions specific to young men who have sex with women. This research will test the efficacy of such an intervention in one of the highest risk populations in the United States.